The present invention relates to a rotary selector switch, and more specifically, to a miniature rotary selector switch assembly which is most suited for installation on a circuit board. Recently there has been a strong demand in the market for a miniature rotary selector switch of this sort.
A prior art rotary selector switch has a rotary rotatably held in a cavity formed by a housing and a case. With the rotation of the rotor, a wiper arranged on the rotor slidingly rotates on the housing base on which are disposed fixed contact elements, thereby to electrically connect at least one of the fixed contact elements to one of the remaining fixed contact elements.
The type of rotary selector switch assembly described above is in fact known and commercially available in the market. The known rotary selector switch assembly is provided with a rotor stopper means.
As shown in FIGS. 17 and 18, a rotor shaft (a) equipped with a rotor fitted therearound (not shown) has a ring (c) fitted therearound. The ring (c) is provided with an arm (b) projected radially outwardly therefrom, while a stopper base (e) embedded in a housing (d) underneath the ring (c) is provided with a plurality of holes, as shown by letters f1, f2 . . . into which desired pins (g) are fixedly inserted.
When the rotor shaft (a) is rotated together with the ring (c) in a clockwise or a counterclockwise direction by means of a handle (h), the projection (b) is slidingly rotated in the same direction and abuts against the stopper pins (g) whereby a further rotation of rotor shaft (a) is blocked.
The prior art rotor stopper means described above requires a complicated manufacturing procedure. This is a result of the complicated assembling of component parts including a rotor shaft, a ring having an arm, a stopper base and a plurality of holes defined in the base etc. Furthermore, an accurate stop position of the rotor shaft may not be obtained because of backlash created by the one way abutment of the projection against the stopper pin.
Since the miniature rotary selector switches are sealed units, the mechanism is not visible to an operator, who must, therefore, have some audible indication that the rotor is making a stepping rotation. Therefore, the prior art rotary selector switch is further provided with an audible indication means which yields an audible click whenever the rotor makes a stepping rotation. Such audible indication means is hereinafter referred to as a click mechanism.
A click mechanism used in the known rotary selector switch is as follows: A rotor comprised of plastic material housed in a cavity formed by a housing of plastic material and a case is provided with a rotor arm extended circumferentially and radially therearound and an end of the rotor arm is arranged to touch stepped portions disposed inside wall of the housing. As the rotor is rotated, as by the rotation of a screw driver or the like engaged in a slot defined in the upper surface thereof, the rotor arm is also rotated steppingly engaged with the stepped portions by turns so that the rotation angle of rotor may be recognized by looking at an arrow head associated with the slot which points to a scale arranged on the case or may be recognized by an audible click yielded by the sliding engagement between the stepped portion and the rotor arm.
The prior art click mechanism described above requires a complicated manufacturing procedure because of the inclusion of so many component parts of considerably large size with resultant difficulty of producing a thin rotary selector switch having a small physical size in order to meet a market demand as heretofore explained.
The prior art rotary selector switch referred to above has a wiper arranged on the rotor during the rotation of which the wiper rotates slidingly on the inner base of the housing on which are disposed fixed contact elements to electrically connect at least one of the fixed contact elements to one of the remaining fixed contacts.
The sliding rotation of the wiper as described above usually produces undesirable powder by dint of tear and wear of the wiper and the housing base due to friction therebetween. The powder thus produced is usually formed into a chain like a piece of yarn due to a frequent sweeping of the powder on the base by means of the rotating wiper.
When the wiper electrically connects at least one of the elements to one of the remaining contact elements as heretofore explained, the chain of powder sometimes spans some of the remaining unconnected contact elements and one of the contact elements already electrically connected via the wiper. This brings forth undesirable electrical leakage between the two contact elements with a result that the rotary selector switch may not achieve the expected efficiency.